Figure 6. Stromatolites in dolomitic marble, 5 km south of
Bancroft in southern Ontario. This marble unit is late
Proterozoic and part of the complex sedimentary succession. The
once circular domal structures have been deformed to the oval
shape by metamorphism. Stromatolites are now being found
throughout the Precambrian area of southern Ontario. Photo by
J.R. Wakefield (1987), witnessed by M. Easton.

Figure 7. Domal stromatolites on an island on Belmont Lake,
near Cordova Mines, 40 km south of Bancroft. These reside in a
dolomitic marble unit which is part of the Grenville Supergroup,
and is older than the pegmatite dikes and calcite vein-dikes
where Po halos are found. Photo courtesy of R.M. Easton.